<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title></title>
</head>
<body>
    <h1>这是主标题</h1>
    <button>修改</button>
</body>
<script src="../lib/jquery.min.js"></script>

<script>
    // var btn=document.querySelector("button")
    // btn.addEventListener('click',function(){
    //     document.querySelector('h1').innerHTML="尼吗死了"
    // })
    $('button').click(function(){
        document.querySelector('h1').innerHTML="尼吗死了"
    })
</script>
</html>